Adjustable spindle assembly for a grass trimmer

ABSTRACT

An adjustable spindle assembly with a spindle housing, a grooved spindle shaft rotatably connected to the spindle housing, a pulley connected to one end of the grooved spindle shaft, a mow ball rotatably connected to a second end of the grooved spindle shaft, and a string carrier assembly connected in between the spindle housing and the mow ball. The string carrier assembly includes a pair of string guides and string holders for securing cutting string to the string carrier assembly without the use of tools. In addition, the string carrier assembly can be adjusted between the spindle housing and the mow ball without the use of tools.

BACKGROUND OF THE INVENTION

The present invention relates generally to a spindle assembly for arotary grass trimmer.

More particularly, this invention pertains to an adjustable spindleassembly for a push-type rotary grass trimmer that includes a mow ballrotatably connected to a spindle shaft and allows the attachment ofcutting strings or filaments without the use of tools.

Although spindle assemblies for rotary grass trimmers are known in theart, the current versions have several problems. For example, U.S. Pat.No. 5,313,770, issued to Smothers on May 24, 1994 and entitled“Jam-Proof Rotary Weed Cutter,” discloses a push-type grass trimmerhaving a spool rigidly connected to a drive shaft. The shaft and spoolare driven at a high rate of speed by a motor and, when the trimmer isused, the spool comes into contact with the ground a significant amountof time. As a result, the spool rubs against the ground, wears down, andmust be replaced. This result is undesirable because replacing the spoolcosts time and money. As a result, there is a need for a spindleassembly that reduces the amount of wear on the spool when the spool isin use.

Current spindle assembles also require the use of tools to secure thecutting string or filament to the spool and to adjust the cutting heightof the string. U.S. Pat. No. 5,862,655, issued to Altamirano et al. onJan. 26, 1999 and entitled “Adjustable Mowing and Trimming Apparatus,”discloses a push-type grass trimmer that includes an adjustable trimmerhead that is connected to a spindle head using a threaded fastener,i.e., a bolt and nut. In addition, the cutting string is also connectedto the trimmer head using a bolt and nut. U.S. Pat. No. 6,052,974,issued to Harb on Apr. 25, 2000 and entitled “Adjustable Height Head ForString Trimmer,” also discloses a string trimmer that uses bolts tosecure the cutting string to the trimmer head and to secure theadjustable trimmer head in place.

Since bolts are used to secure the trimmer head and cutting string, aseparate tool, such as a wrench, must be used to loosen or tighten thebolts in order to adjust the cutting height or to replace the cuttingstring. The requirement for a separate tool is undesirable because, insome cases, the required tool may not be readily available. Furthermore,the use of a bolt and nut to secure the trimmer head and cutting stringincreases the amount of time it takes to replace the cutting string oradjust the height of the trimmer head. Thus, there is a need for aspindle assembly that includes a means for adjusting the cutting heightof the trimmer head and attaching the string to the trimmer head thatdoes not require the use of a separate tool.

What is needed, then, is a spindle assembly that reduces the amount ofwear on the spool and eliminates the need for a separate tool to adjustthe cutting height and to replace the cutting string.

SUMMARY OF THE INVENTION

The present invention satisfies the above described need by providing aspindle assembly that includes a spool, or alternatively, a mow ball,that is rotatably connected to a spindle shaft, a string assembly thatis adjustably connected to the spindle shaft between a spindle housingand the mow ball, and wherein the string assembly includes a pair ofstring guides and string holders for securing cutting string to thestring assembly without a separate tool.

In one embodiment, the present invention includes a spindle housing, aspindle shaft rotatably connected to the spindle housing, a pulleyconnected to one end of the spindle shaft, a mow ball rotatablyconnected to the opposite end of the spindle shaft, and a string carrierplate having a pair of string guides and s-shaped string holdersconnected between the spindle housing and the mow ball.

In a second embodiment, the spindle assembly of the present inventionincludes a spindle housing, a grooved spindle shaft rotatably connectedto the spindle housing, a pulley connected to one end of the groovedspindle shaft, a mow ball rotatably connected to the opposite end of thegrooved spindle shaft, and a string carrier assembly adjustablyconnected to the grooved spindle shaft between the spindle housing andthe mow ball. The grooved spindle shaft includes a series of lockinggrooves and the string carrier assembly includes a locking slide and aspring, which can be used in conjunction with the locking grooves tosecure the string carrier assembly at various positions between thespindle housing and the mow ball without using a separate tool. Thestring carrier assembly includes a string carrier plate that includes apair of string guides and s-shaped string holders that may be used tosecure cutting string to the string carrier plate without using aseparate tool.

In a third embodiment, the spindle assembly of the present inventionincludes a spindle housing, a keyed spindle shaft rotatably connected tothe spindle housing, a pulley connected to one end of the keyed spindleshaft, a mow ball rotatably connected to the opposite end of the keyedspindle shaft, an exteriorly threaded height adjustment tube connectedto the mow ball, and a string cutting assembly adjustably connected tothe height adjustment tube between the spindle housing and the mow ballusing a locking plate. The string cutting assembly includes a threadedopening for receiving the threaded portion of the height adjustment tubeand can be adjusted by releasing the locking plate, rotating the stringcutting assembly with respect to the height adjustment tube clockwise orcounterclockwise, and engaging the locking plate. The string cuttingassembly includes a pair of v-shaped string holders for securing cuttingstring to the string cutting assembly without using a separate tool.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a first embodiment of the presentinvention.

FIG. 2 is a sectional view of the first embodiment of the presentinvention.

FIG. 3 is an isometric view of the string carrier plate of the firstembodiment.

FIG. 4 is an isometric view of a second embodiment of the presentinvention.

FIG. 5 is a sectional view of the second embodiment of the presentinvention.

FIG. 6 is an isometric view of the adjustable string carrier assembly ofthe second embodiment.

FIG. 7 is an isometric view of a third embodiment of the presentinvention.

FIG. 8 is a sectional view of the third embodiment of the presentinvention.

FIG. 9 is an isometric view of the string cutting assembly of the thirdembodiment.

FIG. 10 is an isometric view of the locking plate of the thirdembodiment.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, a first embodiment of the present inventionincludes a spindle housing 10 having a circular opening 12 definedtherein. The spindle housing 10 is designed to be connected toconventional wheeled lawn trimmers (not shown) and may be varied tofacilitate connection to different types of wheeled lawn trimmers.

A spindle shaft 14 is rotatably coupled to the spindle housing 10 usingthe opening 12 and a pair of bearings 16. The bearings 16 are held inplace using a bearing set collar/grip ring 18. A pulley 20 is connectedto one end of the spindle shaft 14 using a lock washer and a pulley nut(not shown), and is separated from the spindle housing 10 using a pulleyspacer 22.

A mow ball 24 is rotatably connected to the opposite end of the spindleshaft 14 using a bearing 26 (which is identical to the pair of bearings16 referenced previously), a retaining ring 28, and a bearing cover 30.The retaining ring 28 holds the bearing 26 in place and the bearingcover 30 prevents dirt, grass, and other abrasive substances fromcontacting the bearing.

A string carrier plate 32 is connected to the spindle shaft 14 inbetween the spindle housing 10 and the mow ball 24. In addition, thestring carrier plate 32 is separated from the mow ball 22 using a stringcarrier spacer 34.

Referring to FIG. 3, the string carrier plate 32 includes a pair ofstring guides 36 for guiding cutting string 38 onto the string carrierplate 32 and a pair of s-shaped string holders 40 for securing thecutting string 38 to the string carrier plate 32. The string guides 36include openings 42, which are designed to act as guides for the cuttingstring 38. The s-shaped string holders 40 are designed to hold thecutting string 38 securely in place and include a raised lip portion 44and a clamping portion 46. The raised lip portion 44 is biased againstthe underside 48 of the string carrier plate 32 and is designed to betemporarily raised to allow cutting string 38 to pass between the raisedlip portion 44 and the underside 48 of the string carrier plate 32.

To secure the cutting string 38 on the string carrier plate 32, onesimply folds one piece of cutting string 38 in half, forming a loop atone end. This loop is then passed through one of the string guideopenings 42 and lowered down around the raised lip portion 44 of thestring holder 40. Finally, the cutting string 38 is pulled against theraised lip portion 44 of the string holder 40 until the loop of thecutting string 38 slides underneath the raised lip portion 44 into theclamping portion 46. Because the raised lip portion 44 is biased againstthe underside 48 of the string carrier plate 32, the cutting string 38is effectively clamped between the clamping portion 46 and the underside48 of the string carrier plate 32.

Referring to FIGS. 4-6, a second embodiment of the present invention isshown that is identical to the first embodiment except for the spindleshaft 14 and the string carrier plate 32. More specifically, the secondembodiment replaces the spindle shaft 14 with a grooved spindle shaft 50and the string carrier plate 32 with an adjustable string carrierassembly 52.

The grooved spindle shaft 50 (FIG. 5) is rotatably coupled to thespindle housing 10 using a pair of bearings 16 and the opening 12. Onceagain, the bearings 16 are contained in the opening 12 using a bearingset collar/grip ring 18. The grooved spindle shaft 50 includes a seriesof rectangular-shaped locking grooves 54 along the lower portion 56 ofthe grooved spindle shaft 50 below the spindle housing 10.

The adjustable string carrier assembly 52 includes a mounting assembly58 connected to the string carrier plate 32 used in the firstembodiment. The mounting assembly 58 (FIG. 6) is adjustably connected tothe grooved spindle shaft 50 between the mow ball 24 and the spindlehousing 10 using the locking grooves 54, a locking slide 60, and a 1.5inch compression spring 62. The 1.5-inch compression spring 62 ispositioned in the mounting assembly 58 so that one end presses againstan inner portion 64 of the mounting assembly 58 and the other endpresses against the locking slide 60, thereby biasing the locking slide60 into one of the locking grooves 54. By pressing against the oppositeend of the locking slide 60, which extends outward from the oppositeside of the mounting assembly 58 through a locking slide opening 59(FIGS. 4 and 6), the 1.5-inch compression spring 62 is compressed andthe locking slide 60 is disengaged from the locking grooves 54. As aresult, the mounting assembly 58 may be adjusted upward toward thespindle housing 10 or downward toward the mow ball 24.

Referring to FIGS. 7-10, a third embodiment of the present invention isshown. This embodiment includes a spindle housing 10 having an opening12 and a mow ball 24 as shown in the first and second embodiments. Akeyed spindle shaft 66 (FIG. 8) is rotatably connected to the spindlehousing 10 using the opening 12 and a pair of bearings 16. As was thecase with the first and second embodiments, the bearings 16 are held inplace using a bearing set collar/grip ring 18. In a similar manner, apulley 20 is connected to one end of the keyed spindle shaft 66 using alock washer and a pulley nut (not shown), and is separated from thespindle housing 10 using a pulley spacer 22.

This embodiment also includes a height adjustment tube 68 (FIG. 9) thatis connected to the mow ball 24, and includes a keyed inner portion 70and an exterior threaded portion 72. The keyed inner portion 70 matchesthe keyed spindle shaft 66 and allows the keyed spindle shaft 66 to beinserted into the height adjustment tube 68. Furthermore, because thekeyed spindle shaft 66 and the keyed inner portion 70 are mated togetherwhen the keyed spindle shaft 66 is inserted into the height adjustmenttube 68, the keyed spindle shaft 66 and the height adjustment tube 68rotate together when the keyed spindle shaft 66 is rotated. The exteriorthreaded portion 72 includes flat locking portions 74 on opposite sidesand along the length of the height adjustment tube 68.

The third embodiment further includes a string cutting assembly 76 thatincludes a string mount 78 and a cutting disk 80. The string mount 78includes a threaded opening 82, a pair of triangular-shaped stringholders 84 (FIG. 7), and a locking plate opening 86 (FIG. 9). Thethreaded opening 82 is threaded onto the height adjustment tube 68 andthe string mount 78 can be moved upward and downward by rotating thethreaded opening 82 with respect to the height adjustment tube 68. Apair of locking plate guides 69 (FIG. 9) are positioned on both sides ofthe locking plate opening 86 inside the string mount 78 and are used toguide the locking plate 98 when it is moved back and forth within thelocking plate opening 86.

The triangular-shaped string holders 84 (FIG. 7) include a stringholding groove 88 (FIG. 9) connected between two string openings 90 andlocated on an upper portion of the triangular-shaped string holders 84.The triangular-shaped string holders 84 also include a pair of v-shapedstring holding portions 92 located on a lower portion of thetriangular-shaped string holders 84.

The cutting disk 80 is connected to the string mount 78 and includes apair of tabs 94 (FIG. 9) that are aligned with the triangular-shapedstring holders 84. In addition, the tabs 94 include a pair of ovalopenings 96 that are aligned with the v-shaped string holding portions92. In use, the cutting string 38 is passed through the string openings90 into the string holding groove 88, and each end of the cutting string38 is passed through the oval openings 96 and secured into the v-shapedholding portions 92.

The string cutting assembly 76 is secured in place along the heightadjustment tube 68 using a locking plate 98 (FIG. 10) and the flatlocking portions 74 of the height adjustment tube 68. The locking plate98 includes a circular opening 100 for receiving the exterior threadedportion 72 of the height adjustment tube 68 and a rectangular-shapedopening 102 for receiving the flat locking portions 70 of the heightadjustment tube 68. In addition, rectangular-shaped opening 102 isflanked by a pair of locking tabs 104 (FIG. 9) designed to be pressedagainst the flat locking portions 74 of the height adjustment tube 68 inorder to lock the string cutting assembly 76 in place with respect tothe height adjustment tube 68. Finally, the locking plate 98 alsoincludes a pair of guide tabs 101 (FIG. 9) and a pair of locking flaps106 (FIGS. 9 and 10). The guide tabs 101 are used with the locking plateguides 69 to guide the locking plate 98 when it is moved back and forthwithin the locking plate opening 86. The locking flaps 106 arepositioned in a pair of rectangular openings 108 (FIG. 9) in the stringmount 78 in order to restrict the movement of the locking plate 98 intoand out of the locking plate opening 86.

To adjust the height of the string cutting assembly 76, the lockingplate 98 is moved until the circular opening 100 is aligned with theexterior threaded portion 72. In this arrangement, the string mount 78is unlocked and can be rotated with respect to the height adjustmenttube 68, causing the string cutting assembly 76 to move up or down alongthe height adjustment tube 68. Once the string mount 78 is moved to adesired location, the locking plate 98 is moved until therectangular-shaped opening 102 is aligned with the flat locking portions74 of the height adjustment tube 68. As a result, the string mount 78 islocked and cannot be rotated with respect to the height adjustment tube68.

Finally, in all three of the embodiments discussed above, a replaceablewear point 110 (FIGS. 7 and 8) may be connected to a lower portion ofthe mow ball 24 to further reduce wear on the mow ball 24. As such, thewear point 110 may be made of plastic or some other suitable type ofmaterial and is designed to snap into the mow ball 24.

Thus, although there have been described particular embodiments of thepresent invention of a new and useful “Adjustable Spindle Assembly For AGrass Trimmer,” it is not intended that such references be construed aslimitations upon the scope of this invention except as set forth in thefollowing claims.

The invention claimed is:
 1. An adjustable spindle assembly, comprising:a spindle housing; a grooved spindle shaft with a plurality of lockinggrooves, rotatably coupled to the spindle housing; a pulley connected toone end of the grooved spindle shaft; a mow ball rotatably connected toa second end of the grooved spindle shaft; an adjustable string carrierassembly adjustably connected to the grooved spindle shaft intermediatethe spindle housing and the mow ball, the adjustable string carrierassembly comprising a mounting assembly and a string carrier plate; themounting assembly further comprising a locking slide positioned adjacentto the grooved spindle shaft and a spring adapted to bias the lockingslide into one of the locking grooves thereby fixing the mountingassembly in place with respect to the grooved spindle shaft; and thestring carrier plate further comprising a string guide and a S-shapedstring holder, the S-shaped string holder comprising a raised lipportion and a clamping portion.